How do I make my model smooth?
Here are a few things you could try:

  select the vertices you want to smooth, right click, select "Smooth Vertices"
  apply the subdivision modifier -> this will make the model have more faces
    
      For more reading here is the  Blender Subdivision Modifier Manual
    
  
  You could shade smooth, in order to do this:
    
        Go to Object data properties > Normals > check the box and select the degree of angle you would like to be auto smoothed
        select the model and go to mesh > normals > recalculate outside
        finally, go to mesh > shading > smooth faces
    

    
I hope one of these helps, good luck with it.